d4450261e5
The original scheme for reporting spurious wakeups was broken - it tried to use printk() from a context which wasn't coherent with the other CPUs, which risks corrupting the printk() data. Fix this by noting the number spurious wakeups, and only report them when we are properly woken - when we will be coherent with the rest of the system. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
130 lines
2.5 KiB
C
130 lines
2.5 KiB
C
/* linux arch/arm/mach-s5pv310/hotplug.c
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*
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* Cloned from linux/arch/arm/mach-realview/hotplug.c
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*
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* Copyright (C) 2002 ARM Ltd.
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/smp.h>
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#include <asm/cacheflush.h>
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extern volatile int pen_release;
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static inline void cpu_enter_lowpower(void)
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{
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unsigned int v;
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flush_cache_all();
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asm volatile(
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" mcr p15, 0, %1, c7, c5, 0\n"
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" mcr p15, 0, %1, c7, c10, 4\n"
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/*
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* Turn off coherency
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*/
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" mrc p15, 0, %0, c1, c0, 1\n"
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" bic %0, %0, #0x20\n"
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" mcr p15, 0, %0, c1, c0, 1\n"
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" mrc p15, 0, %0, c1, c0, 0\n"
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" bic %0, %0, #0x04\n"
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" mcr p15, 0, %0, c1, c0, 0\n"
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: "=&r" (v)
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: "r" (0)
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: "cc");
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}
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static inline void cpu_leave_lowpower(void)
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{
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unsigned int v;
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asm volatile(
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"mrc p15, 0, %0, c1, c0, 0\n"
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" orr %0, %0, #0x04\n"
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" mcr p15, 0, %0, c1, c0, 0\n"
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" mrc p15, 0, %0, c1, c0, 1\n"
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" orr %0, %0, #0x20\n"
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" mcr p15, 0, %0, c1, c0, 1\n"
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: "=&r" (v)
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:
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: "cc");
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}
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static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
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{
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/*
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* there is no power-control hardware on this platform, so all
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* we can do is put the core into WFI; this is safe as the calling
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* code will have already disabled interrupts
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*/
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for (;;) {
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/*
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* here's the WFI
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*/
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asm(".word 0xe320f003\n"
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:
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:
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: "memory", "cc");
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if (pen_release == cpu) {
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/*
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* OK, proper wakeup, we're done
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*/
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break;
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}
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/*
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* Getting here, means that we have come out of WFI without
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* having been woken up - this shouldn't happen
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*
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* Just note it happening - when we're woken, we can report
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* its occurrence.
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*/
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(*spurious)++;
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}
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}
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int platform_cpu_kill(unsigned int cpu)
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{
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return 1;
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}
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/*
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* platform-specific code to shutdown a CPU
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*
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* Called with IRQs disabled
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*/
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void platform_cpu_die(unsigned int cpu)
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{
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int spurious = 0;
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/*
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* we're ready for shutdown now, so do it
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*/
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cpu_enter_lowpower();
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platform_do_lowpower(cpu, &spurious);
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/*
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* bring this CPU back into the world of cache
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* coherency, and then restore interrupts
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*/
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cpu_leave_lowpower();
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if (spurious)
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pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
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}
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int platform_cpu_disable(unsigned int cpu)
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{
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/*
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* we don't allow CPU 0 to be shutdown (it is still too special
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* e.g. clock tick interrupts)
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*/
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return cpu == 0 ? -EPERM : 0;
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}
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